As mobile devices have been increasingly developed, and the demand for such mobile devices has increased, the demand for secondary batteries has also sharply increased. Among such secondary batteries is a lithium secondary battery exhibiting high energy density and operating voltage and excellent charge retention and service-life characteristics, which has been widely used as an energy source for various electronic products as well as various kinds of mobile devices.
Depending upon the types of devices in which secondary batteries are used, the secondary batteries may be configured to have a detachable type structure in which the secondary batteries can be easily inserted into and removed from the devices or an embedded type structure in which the secondary batteries are embedded in the devices. For example, secondary batteries used in conventional mobile devices may be configured to have a detachable type structure in which the secondary batteries can be inserted into or removed from the mobile devices as needed. On the other hand, secondary batteries used in other devices, such as some mobile phones, tablet personal computers (PCs), and smart pads, may be configured to have an embedded type structure.
Among such secondary batteries is a lithium secondary battery, which is widely used. A secondary battery includes anode and cathode terminals electrically connected to a device in which the secondary battery is mounted and a safety element to effectively control an abnormal state of the secondary battery, such as overcharge of the secondary battery or overcurrent in the secondary battery. Examples of the safety element may include a positive temperature coefficient (PTC) element and a protection circuit module (PCM).
In general, an embedded type secondary battery pack uses a plate-shaped battery cell, which is suitable for electrical connection, and a safety element, such as a PCM, is connected to a battery cell including anode and cathode terminals via a conductive nickel plate by welding or soldering. The anode and cathode terminals contact anode and cathode terminal parts of the PCM such that the anode and cathode terminals are electrically connected to an external input and output terminal formed at the PCM. A connector is electrically connected to the external input and output terminal.
In a conventional secondary battery pack, the connector is connected to a device in a state in which the connector protrudes outward from the battery pack. For this reason, it is necessary to provide the interior of the device with an additional space in which the connector will be located although a space necessary to form the connector is present in the battery pack.
In addition, an expensive flexible board is used to interconnect the connector protruding outward from the battery pack and the PCM. As a result, manufacturing cost is increased.
Therefore, there is a high necessity for a secondary battery pack, from which a protruding connector is removed to improve spatial efficiency and to reduce manufacturing cost.